Holographic data storage based on polarization techniques is proposed. Angular and shift multiplexing techniques, as well as polarization multiplexing, are developed to increase storage capacity. Some experimental results are presented.

In this paper we theoretically study the responsivity of Metal-Insulator-Metal nanostructures to light illumination over a broad wavelength band (1 - 25 microns) and we examine the role of a local field enhancement and electrostatic field on the responsivity.

This paper presents a new model of optical channel allocation named “IRBUS” for improving the operation of a DWDM light source multiplexing by not have to use an optical filter in the DWDM de-multiplexer device. By our method can reduce transmission loss in case of the number of channels are plentiful and each of the channels is nearby that be found in Dense Wavelength Division Multiplexing (DWDM) Systems. The transmission loss is called “Four-Wave Mixing (FWM)” caused by the nonlinearity of the optical fiber signal. The results of numerical computation shown that the IRBUS model can decrease average FWM efficiency from -12.03dBm to -28.27dBm indicated that the remains FWM value are less than other methods and can also reduce the BER probabilities from - 5dBm to -19.75 dBm.

It is well known that when two beams (object and reference) are incident on a recording material, high order diffraction may be observed during both the writing and reading of the hologram. These higher or non-Bragg orders contain the phase conjugate and the phase amplified versions of the object. In this talk, the utility of Bragg and non-Bragg orders during holographic construction and reconstruction using photorefractive materials and photothermoplastics is investigated with applications to object shape determination and deformation. Specifically, we discuss applications of non-Bragg orders in the 3d reconstruction of objects, and holographic interferometry using Bragg order to determine object attitude and deformation. The advantages of using non-Bragg orders (viz., phase conjugate and phase doubling) are also discussed.

Pulsed laser deposition of BiSrCaCuO on MgO (100) using Q-switched Nd:YAG nanosecond laser operating at λ= 1064 nm (ns-PLD) and mode-locked Ti:Sa femtosecond laser at λ= 785 nm (fs-PLD) were performed. Rough surface with spheriodal morphology is the general microstructure of the deposited material from both nanosecond and femtosecond laser ablation. Femtosecond PLD resulted to granular morphology containing both BSCCO phase and rod-like Cu₂O grains. Unlike ns-PLD, fs-PLD produced polycrystalline films even without heat treatment. These results indicate that two distinct ablation characteristic for ns-PLD and fs-PLD of BSCCO.

The influence of substrate heat treatment on the crystallinity and surface morphology of Nd:YAG thin films on Si (111) substrate grown by femtosecond pulsed laser depostion was investigated. A mode-locked 300 mW fs Ti:Sapphire laser was used to grow the Nd:YAG on the Si (111) substrate. The substrate temperature was varied from 300°C to 600°C while keeping the same deposition pressure to 10^-6 mbar for 180 minutes. Post deposition was performed from 400°C to 600°C for 180 minutes. The SEM reveals granular surface with different microstructural features depending on the growth parameters. The XRD patterns show preferential growth at (521) direction after post heat treatment. However, higher temperature results to degradation of crystalline qualities of the films.

In this paper, we have solved nonlinear coupled-mode equations valid for light propagation in a one-dimensional photonic crystal by using numerical expression. Moreover, the medium in this problem has been considered as a nonlinear x ⁽³⁾ material. The numerical results have been used to calculate the conversion efficiency in nondepleted-pump limit. The results have been shown us that the maximum conversion efficiency of third-harmonic generation could be occurred when the fundamental field has been tuned near the lower band-edge of photonic band-gap that band-edge phase matched condition has been satisfied.

Tantalum oxide (Ta_xO_y) as high refractive index material has been grown on p-type silicon and quartz substrates by R.F. magnetron sputtering with our innovative technique called “reactive-gas timing”. The reactive gas timing technique is an on-off time period sequence between argon (Ar) and oxygen (O₂) plasma during sputtering process. The technique of gas-timing plays the effect on the properties of Ta_xO_y thin film. The bombarded Ar-plasma was varied at 2, 5 and 8 sec, while the period of reactive O₂-plasma was kept at 5 sec in this experiment. The physical and optical properties were investigated by using X-ray diffraction (XRD), Atomic Force Microscope (AMF), UV-Visible spectrometer and Spectroscopic Ellipsometer, respectively. The XRD spectra and AFM photographs show all films are amorphous phase with smooth feature. Meanwhile the transmittance of sputtered thin film decreases with 10% and the absorption edge shifts to lower energy with the increasing of the argon period from 2 sec to 8 sec. The refractive index as showed by ellipsometry slightly increases from 2.08 to 2.17 at wavelength 550 nm with the increasing of argon period from 2 sec to 8 sec. The increasing of the refractive index might dues to tantalum (Ta) rich which consists in thin films. The Ar-plasma period in the deposited film plays an important role on the properties of the Ta_xO_y thin films especially as optical refractive index material.

The silicon-on-insulator (SOI) technology is currently recognized as the most viable silicon photonics platform technology for the integration of photonic components onto a silicon wafer, especially silicon waveguide structures. Although a number of photonic components can be manufactured in the technology, the realization of a silicon-based light source in this platform technology is still problematic. The SOI technology, however, is also one of the important vehicles to integrate nanometer scale CMOS integrated circuits. This work describes the design and characterization of silicon nanowire structures in SOI technology to be implemented as light sources, especially as the source for short-haul optical data communication links. Since the light emission also covers the visible region, micro display applications are also envisaged. Building on our previous work in SOI light sources, pn junctions are manufactured in an array of nanowires for coupling into optical fibers for CMOS optical data communications up to a few hundred meters. Since the photon generation is due to hot electron intraband relaxation processes, the carriers must be excited in a fairly large electric field. This is achieved by placing the pn junction into avalanche breakdown. In an effort to reduce the operating voltage, and at the same time increase the average electron energy, a reach-through device structure is implemented. The average electric field in the pn junction is increased using reach-through, causing the electrons within the junction to be higher. This will increase the short wavelength emission, especially in the visible region. We believe the SOI light sources are fully compatible with modern CMOS technologies based on SOI and may provide such technologies with a much needed light source as part of the circuit designer’s toolkit. Integrating light sources in CMOS ICs will allow capitalizing on its widespread use in electronics.

A technique for the localization of 3-D refractive test objects is presented. It uses the statistical behavior of axially propagated wavefronts as a metric to determine object location. The wavefront is obtained using digital holography. The wavefront phase is plotted at equally-spaced axial planes within the wavelength of the light source used. For each transverse phase plot, standard deviation (SD) values are obtained. The axial variation of the SD values yield a contrast map showing the spatial features of the wavefront. To locate the test object along the axial direction, the contrast maps are correlated to a Gaussian test function. The test phase objects objects are transparent adhesive films placed on opposite sides of a 1-mm thick glass slide. This is then mounted approximately 77 mm from the camera plane. Using the proposed technique, the axial distance between the transparent films was determined to be 1.0112mm which indicates the glass slide thickness. The correlation plot yields a well-behaved curve facilitating the precise localization of the test objects.

The silicon carbide layer was deposited on Si substrate by Plasma Enhanced Chemical Vapor Deposition method and it was shown its RFTIR spectrum is periodic in near and medium IR range by using this property refractive index of thin film was calculated. It was shown both deposition rate and uniformity of thin film were decreased by increasing substrate temperature. We also showed although the refractive index and deposition rate of SiC layer depend on the substrate temperature, and the roughness of surface was decreased but refractive index was increased by increasing substrate temperature It was shown the refractive index increases by annealing SiC thin film, at 900 °C.

In this work we have studied the interaction of a laser pulse with single-walled metallic carbon nanotubes. We have discussed the Rabi oscillations in zigzag carbon nanotubes based on the two-band model. We have shown the interband coupling coefficient enters into the probability of excitation.

Based on our previous work on light penetration-based silkworm gender identification, we find that unwanted optical noises scattering from the surrounding area near the silkworm pupa and the transparent support are sometimes analyzed and misinterpreted leading to incorrect silkworm gender identification. To alleviate this issue, we place a small rectangular hole on a transparent support so that it not only helps the user precisely place the silkworm pupa but also functions as a region of interest (ROI) for blocking unwanted optical noises and for roughly locating the abdomen region in the image for ease of image processing. Apart from the external ROI, we also assign a smaller ROI inside the image in order to remove strong scattering light from all edges of the external ROI and at the same time speed up our image processing operations. With only the external ROI in function, our experiment shows a measured 86% total accuracy in identifying gender of 120 silkworm pupae with a measured average processing time of 38 ms. Combining the external ROI and the image ROI together revamps the total accuracy in identifying the silkworm gender to 95% with a measured faster 18 ms processing time.

Combining confocal microscopy and optical tweezers, we map out the spatial distribution of the particle concentrations of quantum dots, fluorescent HIV pseudo virus particles and polystyrene nanospheres in an optical trap. By analyzing the Boltzmann distribution of local particle concentrations, we obtain the two-dimension single particle trapping potential profile at the center of the optical trap in the direction perpendicular to the beam propagation. We compare the trapping potential energies of pseudo HIV vesicles and same-sized polystyrene spheres. We also compare the trapping potential energy of polystyrene spheres of a focused Gaussian beam and two modes of cylindrical vector beams.

Dimensions of grains are important factors in evaluating the physical quality of the grains. In this work, we show for the first time that the thickness, the width, and the length of rice grains can be simultaneously measured. Rather than imaging rice grains only above from a two-dimensional plane, our key idea is to insert a tilt reflective surface on the measuring plane such that the side view of the rice grains can be observed at the same time. Demonstration from our prototype shows a very promising result in determining the thickness, the width, and the length of the rice grain with maximum values of 2.20 mm, 3.65 mm, and 10.27 mm, respectively. It offers a very high average resolution of 22 μm and a measured response time of 205 ms. Additional key features include low cost, low components count, and ease of implementation.

A neutral density filter (ND) is one of the basic and important optical components used in optical and photographic systems for controlling intensity of light at all wavelengths. It is typically fabricated by coating appropriate thin films on glass or plastic substrates through an expensive time-consuming and power-hungry thin-film coating system. In this work, we show for the first time how very low-cost NDs can be implemented on a well-known Polydimethylsiloxane (PDMS) material widely used in microfluidic applications. PDMS-based NDs with 10-80% transmission and a broad wavelength operation in a visible spectrum are highlighted.

In this invited paper, we review the theoretical model and performance of an Interferometric Modulator with Phase modulating And Cavity-modulating Components (IMPACC). IMPACC has the highest reported SFDR (e.g., 132 dB-Hz) and offers additional advantages compared to other Mach-Zehnder Interferometer (MZI) based electro-optic modulators (e.g., MZI, ring-assisted MZI or RAMZI). The modulator is based on a unique combination of a RF driven phase-modulator (PM) and a ring resonator (RR) within a MZI interferometer. Both the PM and RR in the IMPACC are simultaneously driven by a RF signal of the same frequency, but not necessarily the same amplitude and phase. Here, we summarize the non-ideal and oftentimes detrimental effects such as: (1) RF bandwidth limitation due to free spectral range (FSR) of the RR, (2) RR waveguide loss, (3) deviation of RR coupling ratio from the ideal value, and (4) unbalanced MZ splitter/coupler on the performance of both IMPACC and RAMZI. We show that proper choice of RF power split ratio and RF phase for IMPACC compensate these negative effects and recover IMPACC’s ideal performance. Unlike RAMZI, this translates to higher device tolerance, added manufacturing flexibility, and superior modulator performance.

A brief review is presented for recent progress in a fully interferometric technique to obtain a set of spectral components of three-dimensional images for usual polychromatic objects. The review includes a principle of method and experimental demonstrations in which the measured object is regarded as spatially incoherent in each spectral component. We also suggest that some alternative ways to realize the same results having different characteristics based on modified synthetic aperture techniques.

In recent years, several activities have been toward optically pumped molecular gas lasers as mid-infrared coherent sources. These have been also motivated by the search of suitable laser media for Hollow-core Optical Fiber Gas Laser (HOFGLAS) and the novel beam combiner. To continue these challenge paths, an optically pumped Hydrogen Iodide (HI) laser is explored by using a comprehensive laser model. HI transitions in the communication band (1.5 μm) are attractive due to a potential mean to be excited by commercial available laser systems. Furthermore, its emission coverage in 5 micron region can be useful for many applications, for example, free-space communication and laser spectroscopy. In the laser model, 30 rotational states in each of the 8 vibrational states of HI are taken into account to allow molecular energy transfer processes such as rotational relaxation and vibrational relaxation. A HI laser under pulsed excitation on a second overtone transition with lasing cascade is possible. The complete lasing cascade originates from the terminal pumped state (vibrational state, V = 3) to the vibrational state, V = 2, from the vibrational state, V = 2 to the vibrational state, V = 1 and finally from the vibrational state, V = 1 to the vibrational ground state. For the full lasing cascade, the laser efficiencies can be approached to 70%. In addition, the lasing behavior of the gas pressure related to the molecular relaxation rates and pressure broadening effects is also investigated. Owing to exceptional frequency tuning properties, the laser output can be manipulated to desired frequencies.

We have studied a method to obtain both three-dimensional (3-D) spatial information and spectral information of a usual polychromatic object by a fully passive interferometric technique that is strongly coupled with digital signal processing^{1- 6}. Our method can be used for a vast range of wavelengths, because no special imaging devices, such as lenses, are required. In addition, coherent light sources are not necessary. A hyperbolic-type volume interferogram⁶ is one type of the volume interferogram, which is used for retrieve the object information, and an interferometer to measure directly this volume interferogram has been introduced³. This paper introduces a method to measure the hyperbolic-type volume interferogram with high sensitivity in fully interferometric 3-D imaging spectrometry. This is accomplished by coupling of interferometer to measure directly the hyperbolic-type volume interferogram and heterodyne detection system⁷ for broadband light. We also report a preliminary experimental result based on the interferometer to measure directly the hyperbolic-type volume interferogram.

In this research, the low cost optical tweezers systems using X-Y stage has been developed by using 5-phase stepping motor. By using sequential double coil driving, we can obtain the driving torque larger than using the single coil driving. The moving scale is fine resolution at 0.2 micrometer. The overall systems based on microcontroller PIC18F458 and joystick controller with LabView® graphical user interface (GUI). The mechanical damping has been included in the system for decreasing the vibrational noise. By using this method, our optical tweezers system is cheaper than the other commercial system that has been used the piezoelectric driving, and still has the same efficiency.

Optical Tweezers are well known for manipulating and tracking microscopic particles used in many biological and microfluidic applications. Trapping birefringent particles, e.g. liquid crystal droplets, gives insight into the aspect of light polarization in optical tweezers. The outstanding properties of liquid crystal droplets are their high refractive index and birefringent property suitable for light angular momentum transfer. Under the microscope, the Maltese cross of radial nematic liquid crystal droplet was observed. Trapped under 1064 nm Optical Tweezers with power lower than 80 mW, the droplet precession around the focal point of the laser beam was observed due to circular polarization of laser. In this study we show that the precession behavior of radial nematic droplet depends on the degree of ellipticity of polarization state of light, power of the laser source and size of the radial nematic droplet, affecting the induced electrical polarization and internal reordering of the droplets. The theoretical explanation and the model of this behavior have also been determined and discussed.

Cell growth and division has been of scientists’ interest for over generations. Several mathematical models have been reported derived from conventional method of cell culture. Here we applied optical tweezers to guide cell division directionally. The patterns of Saccharonmyces bayanus yeast growth was studied under 1064 nm line optical tweezers generated by time-shared multiple optical traps. Yeast growth was found following the path of the generated laser patterns in linear, circular, square and L shapes, speculatively as a result of localized heating effect due to absorption at the focal point.

Retinal recognition by using compression-based joint transform correlator (JTC) is proposed. Recognition performance is quantitatively measured by taking into account effect of imbalanced illuminations and noise presence. The simulation results show that the compression-based JTC has reliable recognition performance for high-contrast retina target. Besides acceleration of image transfer time, the compression of the noise-corrupted retina target images can improve the correlator robustness to noise.

This paper highlights based on author's experience how optics and photonics is applied in Thai agriculture. These include spectral imaging based systems and mobile applications that have been implemented in the last 5 years for rice, fishery, and sericulture. Brief review of optics and photonics in agriculture will also be introduced.

Electricity, Information and Communication Technologies (ICTs) are very important not only in urban areas but also in rural areas. To provide ICTs service in rural areas, sources of electricity and communication infrastructures must be implemented. Electricity is a major condition due to the fact that all electronic devices needed it in order to power on, so that it is impossible to operate any forms of ICTs in areas where the main national grid line is unavailable. Almost rural areas of Thailand where the main national grid line is unavailable have very good sunlight intensity. Photovoltaic is the most effective renewable energy technologies in those areas for meeting electricity needed in areas that are not connected to the main national grid line. In this paper, the efficiency utilization of photovoltaic as source of electricity for broadband satellite communication systems as well as social and economic impact and quality of life of people in rural areas of Thailand are presented. The results show that most rural communities would be able to universally access to the basic telecommunications services such as internet access and public telephone via satellite communication systems. However, in some field case study, broadband internet access via satellite communication may be unnecessary for some rural communities and the most exactly rural communities needed are electricity for household usage and battery charger.

Today, it is understood that conventional ophthalmic lenses can compensate only second-order optical aberrations. To alleviate higher-order aberration factors, a special phase plate with overall phase conjugation to the human eyes is required. Keeping in mind that this special phase plate needs to be practically placed in front of our eyes at an appropriate distance, the longitudinal misalignment can cause additionally unwanted optical aberrations. In this work, we show how a Fourier Optics can simply be applied in analyzing the performance of a phase plate in compensating the occular aberration under longitudinal misalignment. The result will lead to a new way in designing a customized wearable compensating phase device.

In this paper, we have proposed the novel prototype of the portable fingerprint scanner. Using this method, the low coherence digital holography technique has been used to verify fingerprints. In our experiment, the Michelson’s interferometer has been setup first for determining the coherence length of a laser diode with wave length of 635 nm. In our model, the light transmission and reflection properties of the glass slide have been applied. Then, the glass slide has been used as a beam splitter for separating the light to two beams, which are the reference beam and fingerprint image bearing beam. The results show fingerprint pattern, which are reconstructed with numerical method.

We present the improved tunable filter based multispectral imaging system for detecting blood stains on construction materials. Based upon the reflectance and Kubelka Munk absorbance spectra stocked from our previous work, we modify the blood discrimination criteria to make the system more efficient by replacing the old criteria which make use of polynomial fitting with new criteria associated with a few wavelengths images. The newly established criteria are tested to be able to detect blood against other stains almost as efficient as the old criteria, while the number of spectral images required for detecting blood stains are reduced significantly from 64 to 9 spectral images. The reduction of required spectral images will reduce the time needed for image capturing and blood detection criteria application with little sacrificing of the specificity and sensitivity of the system.

High-rise and commercial buildings in urban centers present a great challenge in terms of their energy consumption. Due to maximization of rentable square footage, the preferred urban façade system over the past 50 years has been the “curtain wall”, only a few inches thick and comprised of modular steel or aluminum framing and predominant glass infills. The perceived Achilles heel of these modern glass façade systems is their thermal inefficiency: They are inadequate thermal barriers and exhibit excessive solar gain. The excessive solar gain has a negative impact on lighting and cooling loads of the entire building. This negative impact will be further exacerbated with rising energy costs. However, rather than view the glass façade’s uncontrolled solar gain merely as a weakness contributing to higher energy consumption, the condition could indeed be considered as related to an energy solution. These glass façades can be retrofitted to operate as a provider of daylight and energy for the rest of the building, taking advantage of the overexposure to the sun. With today’s technology, the sun’s abundant renewable energy can be the driving force for the energy transition of these building envelopes. Illumination, thermal energy, and electricity production can be directly supplied from the sun, and when correctly and efficiently managed, they can lead to a significantly less energy-intensive building stock. We propose a multi-purpose, prismatic, louver-based façade to perform both daylight and thermal energy harvesting with a goal of offering a better daylight environment for the occupants, and reduce the energy consumption and carbon footprint of the building. While decentralized air-conditioning units are commonly accepted as façade “plug-ins”, such decentralization could be utilized with more benefits by passively managing the interior space conditions, without using any extra power. Just as living organisms respond and adapt to the environmental changes in their surroundings, the proposed multi-purpose prismatic louver façade can be responsive and resilient to daytime sky conditions, environmental temperatures and occupant needs by exploiting options presented by the three sides of the prismatic louvers. The façade is highly configurable since every side of the prismatic louver façade can perform a different operation. The prism itself operates as a redirector of sunlight from the glass façade to the ceiling and consequently diffuses the sunlight throughout the room, providing higher and more uniform illumination levels. In addition, each side of the prismatic louver can be implemented in multiple ways (e.g., visibly transparent photovoltaic cells, luminescent solar concentrators). The ability to rotate the prismatic louvers along their axes allows the user to expose a set of different surfaces to the sun’s radiation in accordance with different climatic conditions and occupant needs. Thus, the prismatic louvers help achieve a selective control and management of the incoming light that allows us to manipulate the incoming energy for the benefit of the building and its occupants.

We previously showed that a combination of image thresholding, chain coding, elliptic Fourier descriptors, and artificial neural network analysis provided a low false acceptance rate (FAR) and a false rejection rate (FRR) of 11.0% and 19.0%, respectively, in identify Thai jasmine rice from three unwanted rice varieties. In this work, we highlight that only a polynomial function fitting on the determined chain code and the neural network analysis are highly sufficient in obtaining a very low FAR of < 3.0% and a very low 0.3% FRR for the separation of Thai jasmine rice from Chainat 1 (CNT1), Prathumtani 1 (PTT1), and Hom-Pitsanulok (HPSL) rice varieties. With this proposed approach, the analytical time is tremendously suppressed from 4,250 seconds down to 2 seconds, implying extremely high potential in practical deployment.

This paper presents a new method of digital holographic three-dimensional imaging spectrometry. The method is based on the measurement of new type of volume interferogram, called Rotated-Hyperbolic-type volume interferogram, obtained with the existing interferometer. We report the first demonstration of the method in which a monochromatic point source is used as the measured object. The results include 3-D spatial information and spectral information of a monochromatic point source. This experimental result corresponds to the impulse response function defined over a four dimensional (x, y, z, k) space. As a result, the method is confirmed to have the superior imaging characteristics in the z direction.

We present a new microring resonator (MRR)-based optical filter that takes advantage of the improvements that can be gained from cascading two (or more) MRR elements while physically using only one MRR element due to its unique looped-back configuration. This approach avoids the costly problem associated with dynamic control of matching (or aligning) the center-wavelengths coming from the two MRR elements. This new optical filter is a generalization of our previously reported filter (called LOBOUR) based on the Cascaded Over- and Under-coupling Resonator (COUR) architecture. Here, we compare the performance of our filter to four different configurations under the following criteria: (1) lower group delay (GD), and (2) simplified solution to wavelength-drift problem, (3) lower power consumption, (4) narrower linewidth, and (5) better extinction ratio (ER).

We have studied a method to obtain both three-dimensional (3-D) spatial information and spectral information of a usual polychromatic object simultaneously by making use of a specifically designed two-wavefront folding interferometer and signal processing, including synthetic aperture technique, spectral decomposition, and 3-D image retrieval. The method uses only interferometric techniques and signal processing applied to the interferogram generated by propagated light from the measured object^1-2. We call the method the digital holographic 3-D imaging spectrometry. The method is based on measurement of 5-D interferogram. By applying synthetic aperture technique and spectral decomposition to that 5-D interferogram, one obtains a set of complex holograms of different spectral components. From these holograms, 3-D images of multiple spectral components have been retrieved on the basis of the propagation law applied to the 2-D cross-spectral densities. Decomposed continuous spectrum of each light source is also shown to demonstrate a potential applicability to identify materials of a particular part of object under illumination of white light. This paper reports experimental results in retrieving the spectral components of 3-D images of the spatially incoherent light source distribution. The results for depth imaging properties are also demonstrated.

Some green fruits do not change their color from green to yellow when being ripe. As a result, ripeness estimation via color and fluorescent analytical approaches cannot be applied. In this article, we propose and show for the first time how a thermal imaging camera can be used to two-dimensionally classify fruits into different ripeness levels. Our key idea relies on the fact that the mature fruits have higher heat capacity than the immature ones and therefore the change in surface temperature overtime is slower. Our experimental proof of concept using a thermal imaging camera shows a promising result in non-destructively identifying three different ripeness levels of mangoes Mangifera indica L.

In this study, we have observed a SFG microscopic image of the H-Si(111)1×1 surface after pump IR light irradiation. As the results, resonant SFG signals attributed to Si-H stretching vibration disappeared at the irradiated areas, and non-resonant signals were generated at these areas. We also found that there were boundary areas between laser irradiated and non-irradiated areas. Both SFG signals were weak at the boundary areas. As the reason of these modulations of SFG signals, we assumed that the temperature did not sufficiently increase for hydrogen desorption at the boundary areas, since the areas were located at edges of spatial distribution of the pump laser intensity. In order to verify the assumption, we heated the Si surface at 711K, slightly above threshold temperature for activation of hydrogen desorption, and then observe SFG spectra of the Si surface as a function of hydrogen coverage at room temperature. As the results, the intensity of the peak at 2083.7cm^-1 attributed to Si-H stretching vibration reduced as a function of hydrogen deficiency. Also, the peak position shifted toward red side. We simulated dipole-dipole interaction by using coherent potential approximation (CPA) method, and the simulated peak shift was qualitatively consistent with the experimental one. Thus, the peak shift corresponded to dipole-dipole interaction. On the other hand, the experimental peak width also broadened with the coverage reduction. However, the broadening was far wider than that of theoretical width. We suggest that the broadening was attributed to local structure defects and/or influence of neighbor dangling bonds.

In this paper, the surface plasmon resonance (SPR) effects between solid silver (Ag) and Ag-shell nanoparticles (MNPs) in active layer of AgO_x-type super-resolution near-field structure (super-RENS) are numerically investigated and quantitatively compared by means of finite-difference time-domain method. Eight types of MNPs patterns, i.e., structure #1-#8 in active layer of super-RENS are studied. Results show that the proposed structure #3 and #7 in active layer shows higher field intensity than other structures corresponding to their SPR wavelengths. It is found that the structure #7 (square Ag-shell of MNPs) is the best choice in the view point of designing the AgO_x-type super-RENS. This study provides the information to design a super-RENS with superior resolution as well as other applications in nanophotonic devices.

In this work, we numerically investigate the surface plasmon resonance (SPR) effects on a pair of rotational silver nanorod/nanoshell dimer with a finite height of 1000 nm by means of finite element method with three dimensional calculation. The rotational angles of the silver nanorod/nanoshell dimer are chosen θ=0°, θ=25°, θ=45° and θ=90°, respectively. The proposed structure exhibits a red-shifted localized SPR that can tuned over an extended wavelength range by varying the dielectric constant in metal nanoshell and the rotational angle of the silver nanorod/nanoshell dimer. The tunable optical properties on SPR phenomena are attributed to the rotational effect and a larger effective size of dielectric constant that is filled with a higher refractive medium of finite height of metal nanorod/nanoshell. This unique property of a pair of rotational nanorod/nanoshell dimer is highly attractive for serving as resonant center to hold and probe smaller nanostructures, such as biomolecules or quantum dots. Such structures also show significant promise for applications in nano-switch devices, sensing, and surface-enhanced spectroscopy, due to their strong and tunable plasmon resonances.

In this research, effect of milling time on crucial physical structures of commercial TiO₂ powders in form of anatase phase is investigated. The as-received commercial TiO₂ powders were ball-milled with ethanol solvent at room temperature at various operating time ranging from 6-24 hrs. Particle sizes and surface areas of milled powders were characterized by particle analyzer and Brunauer Emmet Teller (BET) method.TiO₂ surface morphologies of the powders milled at various times were monitored by scanning electron microscope. The photocatalytic activities of the milled powders were conducted by mean of the photo-induced degradation against RhB aqueous solution. The results reveal that particle size of the commercial TiO₂ powders can be effectively minimized to few hundred nanometer range depending on milling time. The drastic reduction in their size results to the increasing active surface area of the particles and the enhanced photo-induced activity that was supported by the photodegradation performance. This enhancement can suggest them to the suitability in optical energy harvesting optoelectronic applications including photovoltaic devices, optical based sensors and related environmental-friendly usage.

Publisher’s Note, 8 March 2017: This paper, originally published on 7 June, 2013, was withdrawn at request of the author.

A generation of optical capsules and tweezers array within a modified optical add-drop filter known as PANDA ring resonator with a new concept is proposed. By using dark and bright solitons, the orthogonal tweezers can be formed within the system and observed simultaneously at the output ports. Under the resonant condition, the optical capsules and tweezers generated by dark and bright soliton orthogonal pair where the dark-bright soliton array with different center wavelengths and propagation in to the modified add/drop filter that can be generated the optical capsule. In principle, the molecule/atom is trapped and capsule by the force generated by reverse different combinations of gradient fields and photons interaction within the PANDA ring. In application, the molecules/atoms can be secured by using the dark-bright soliton reverse different combinations (optical capsule). Whereas the dark-bright soliton can be capsule as the molecule/atom, which can be used to molecule/atom transportation increased. Simulation result obtained has shown that the amplified power 12 W of the dark-bright soliton array capsule and with wavelength center around 1.40 - 1.50 μm at drop port and throughput port can be achieved, respectively.

The sample of CuFeO₂ delafossite was synthesized by solid state reaction for studying alcohol gas sensing properties. The Seebeck coefficient and electrical conductivity were measured in the high temperature ranging from 300 to 960 K. The CuFeO₂ gas sensing displays high sensitive to ethyl alcohol gas in sensitivity ranging from 70 to 93 % and responding in 2 to 4 minute. The electronic characterization on the sample exhibits p-type conductor and displays electrical conductivity ranging from 3 to 13 S/cm with activation energy in 49 meV. This study suggests that CuFeO₂ delafossite is a new one to be candidate in oxide material for alcohol gas sensing.

Fluorescence spectroscopy detection has been commonly used in chemical and biochemical applications as it provides a good reliability and high sensitivity. Commercially available fluorescence spectroscopy system is typically bulky and expensive, hence making it inconvenience for on-site measurement which requires portable systems. However, the drawback of small devices is that it has a low detection volume, resulting in low fluorescence signal. In this paper, we report a microfluidic channel implemented with a microlens array for enhancing the performance of fluorescence spectroscopy detection. The microlens array was used to focus an excitation light onto the microchannel, thus expecting the increase in fluorescence detection signal. Both microchannels and microlens arrays were individually fabricated from poly-dimethylsiloxane (PDMS) using low-cost printed-circuit-board master molds. The fabrication and characterization of PDMS-based microlens arrays are discussed. In short, the microlens in plano-convex shape was designed with diameters of 700, 800 and 900 microns. The fabricated microlens arrays were characterized for radius of curvatures, SAGs and focal lengths. The plano-convex microlens array was then integrated into a microfluidic system in order to investigate the overall performance of fluorescence spectroscopy detection. Experiments were conducted with two fluorescence dyes, i.e. Rhodamine 6G and Coumarin 153. The preliminary results revealed that the PDMS microlens array implemented on the designed system shows potential for improving excitation and emission light intensity and, as a consequence, signal to background ratio of the fluorescence spectroscopy detection.

The CuCoO₂ sample has been synthesized by a conventional solid-state reaction method to investigate electronic transport and optical properties for p-type transparent conducting oxide materials. The crystal structure was characterized by XRD. The Seebeck coefficient and electrical conductivity were measured in the high temperature. The UV-VIS-NIR and FTIR spectra were analyzed at room temperature. The XRD peaks confirm the samples forming the delafossite structure phase. The Seebeck coefficient sign confirms the samples displays the p-type conducting. The electronic transport energy for activating free carrier production and conduction contain 0.276 eV and 0.131 eV, respectively. The optical direct gap is 3.65 eV which is a visible-transparent oxide material. These results support that the CuCoO₂ oxide compound is p-type transparent conducting oxide materials.

In this paper, optical phase conjugate beam with the using of different resonator configurations has been investigate. Two types of SPPC resonators were selected to use, the first one is linear resonators formed by crystal surface and the other one is linear resonators formed by single mirror and a photorefractive crystal. In our experiment, cerium doped barium titanate crystal (BaTiO₃ : Ce) and He-Ne laser with wavelength of 632.8 nm have been used. From the results of both cases, the angle of the incident beams is optimum at 37.95° respect to the normal line of the surface that parallel to the c-axis of the crystal. The generating time of OPC beam are 150 seconds and 330 seconds for the first and second type resonators, respectively. The reflection ratios are equal to 8.75% and 5% for the first and second type resonators, respectively (the first type resonators could provide better reflection ratio).